Users with the role external user can be found in the user search, but cannot be added to groups. These are often users who have self-registered in the system. They will be registered with the attribute "external user" and do not have full user rights. With this user role, you can only use the functions of the platform to a limited extent. For example, you cannot be added to a group.
A user administrator can change the user role. For an overview of all user roles and rights available in the system, see the section Roles and rights.